change from address in mailx

Hi,
i am sending mails regulary for updation of data.

The from addresses dispaly like
POP.RECH@skk182.com

i want display like

oracle@skk182.com

can u help me on this.

Input(a):

leodf.s.li@reuters.com
jdfde.yin@reuters.com

output:

reuters@reuters.com
reuters@reuters.com

code:

cat a | sed 's/^.*@/reuters@/'